It is already known and still very usual in, for example, dwelling-houses, offices and administration buildings to provide an electrical power system as a draw-in system or an exposed wiring as a so-called visible mounting. Such a system is inflexible because it uses fixed output points, which are predetermined before the relevant building is constructed. Changes at a later date are very often impossible or extremely difficult to achieve, they cost a considerable amount in terms of money and time and the result is often not aesthetically pleasing.
The disadvantages of these kinds of installations led to provision of so-called wiring channels or contact rails. Wiring channels are normally located visibly on walls and run horizontally along the walls at a height generally level with a top of a desk. Electrical cables in such channels are connectable, for example, to plugs, the location of which can be determined at a later date. Once determined, however, this location is fixed because to change a plug's location new wiring of cables would be required. Contact rails, on the other hand, have the advantage that sheathed cables are replaced by blank conductors conducting along their entire length. Accordingly, a connection can be made at any place along such contact rails without change of the phases or change in the plugs and current consuming elements such as light emitting armatures etc. can be directly connected thereto.
This much needed flexibility of connections at such contact rails was however, made at the cost of safety, becauae the connectors carrying current are easily accessible and children in particular may risk serious injury by touching them inadvertently or otherwise. Normally, therefore, there are strict provisions relating to minimum height of such installations (2.3 meters) and/or for the use of low voltage or low current supply.
These requirements which are, of course, fully justified for safety reasons also severely limit the use of known contact rails.
A typical contact rail is of U-shape with an opening directed downwardly and laterally to the middle of a room and electrical conductors embedded at the inner side of a limb of the U-profile. A typical example of such a contact rail is shown and described in Swedish patent application 71-6528. In this case there is no direct danger of electric shock, as the electric conductors are embedded relatively deeply within electrically isolating material. However, there is still a risk that children may attempt to plug-in items and receive a shock as the space adjacent the voltage carrying conductors can be directly touched through the opening of the contact rail.
It is an object of the present invention to provide a new rail for the supply of electrical current and telephone and the like connections which is designed to be so safe that risk of electric shock or plug-in are reduced to an absolute minimum, so that such a current rail may be safely used as an output rail for high current supply and can be mounted at any height. A further object of the present invention is to enable different phase selections and to do this in a simple safe and reliable manner. Furthermore an inventive rail, although having technical advantages should have a good design, should be relatively cheap to manufacture and should be mounted so as to be changed in a simple quick and safe way, for example in order to be extended and to be mounted around corners and through recesses.